Fabrication and testing of a centrifugal pump

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The content of this presentation is for informational purposes only and is intended only for students attending Portland State University.

The author of this information does not make any claims as to the validity or accuracy of the information or methods presented.

The procedures demonstrated here are potentially dangerous and could result in injury or damage.

Portland State University and the State of Oregon, their officers, employees, agents or volunteers, are not liable or responsible for any injuries, illness, damage or losses which may result from your using the materials or ideas, or from your performing the experiments or procedures depicted in this presentation.

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DISCLAIMER

Examples of Centrifugal Pumps

www.grpumps.com www.oilworksinc.com

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Examples of Impellers

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Pump fabrication

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teams of two students

mostly involves drilling holes

Raw Materials

Ultra-Machinable High-Strength Bearing-Grade Bronze (Alloy 544) Bronze is primarily an alloy of copper and tin. This bronze contains lead, making it easier to machine.

PVC = polyvinyl chloride

PVC is made of long chain molecules with a carbon backbone and hydrogen and chlorine side groups

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Parts and Materials Required for Pump

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McMaster-Carr 2" x 2" PVC gray square bar (type 1, cut 0.9" long)

McMaster-Carr 1/2" thick blue tint PVC sheet (type 1, cut into 2" x 2" squares)

McMaster-Carr 1.6 mm wide, 2.2 mm ID o-ring (viton)

McMaster-Carr 1 1/16" ID x 1 1/4 OD o-ring with 3/32" width

McMaster-Carr PVC clear unreinforced tubing, 3/16" ID, 5/16" OD, 67A (soft), 45 psi

McMaster-Carr nylon barbed tube fitting, 3/16" tube ID, 1/8 NPT male pipe, shite

McMaster-Carr #6 sheet metal screws, 1" long, pan head, phillips, zinc plated

McMaster-Carr Ultra-machinable bearing grade 5/16" dia. bronze rod, alloy 544

Walmart 8" cable ties (~0.095" wide)

Jameco Electronics 9-30V, 0.35A,4930 rpm,44.5 g-cm DC motor (shaft: 0.090" OD & 0.45" long)

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SolidWorks modelsimpeller

(your own design)

pump body

faceplate

other parts &pump assembly

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Impeller must fit inpump body

slightly smaller than motorshaft to allow a press fit

inside radius of impeller cavity is 0.50 inch; making theimpeller radius 0.45 inch leaves a 0.05 inch clearance

the target depth of the impeller cavity is0.5 inches; if this dimension is too large,

the impeller will rub on the face plate

making a little offset here keeps the impeller fromrubbing against the bottom of the impeller cavity

impeller cavity in pump body

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Pump fabrication

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mostly involves drilling holes

The operations below are performed by University technicians(do not do this yourself).

1. Rip the PVC sheet into 2 inch wide strips using a table saw. Then, chop these strips into 2 inch long segments for the pump face plate using a chop saw.

2. Saw the 2 inch x 2 inch PVC rod into a 0.9 inch long segment for the pump body using a chop saw.

table saw chop saw

raw materials

materials after cutting 11

Bushing and Seal: University technicians have fabricated a bushing and seal to prevent your pump from leaking around the DC motor shaft. The seal is made from a bearing grade bronze rod and a small o-ring. The bronze rod is prepared using a lathe.

lathe

STEP 1: bevel bronze rod STEP 2: center drilling with #42 bit STEP 3: make o-ring seat with 13/64 end mill

STEP 4: parting bronze rod STEP 5: glue in o-ring finished bushing / seal 12

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Pump fabricated. Let’s test it.

Pump testing

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• See how high your pump can pump water• Measure electrical current and voltage as well as the mass of water collected at

several more heights (or pump heads) up to a maximum of 72 inches• Generate a plot of pump head versus flow rate• Generate a plot of pump efficiency versus pump head

head or height that water is pumped

(in)

electrical current needed to power pump

(A)

voltage across pump leads

(V)

length of time, Δt, that water is collected

(s)

mass of water collected over Δt

(g)

height 1 20

height 2 45

… height 8 (or more) 35

h = head

m = mass of water collected

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What to turn in1. A title page2. A concise, well-written executive summary that includes . . .

a. A couple of introductory sentences describing the projectb. The maximum pump head (meters)c. The peak flow rate (liters per minute)d. Typical voltage (V) and current measurements (A)e. The peak efficiency (%) and the head (meters) at which the peak efficiency occurs

3. Photos of you and your partner(s) during pump fabrication and testing4. Your Excel spreadsheet containing the raw data and computed values:5. A detailed hand calculation using engineering format showing all

calculations for a data point in your Excel spreadsheet (include units!!)6. A plot of pump head versus (meters) flow rate (liters per minute)7. A plot of pump efficiency (%) versus pump head (meters)

Be sure to put the items in the order listed (1, 2, 3, . . . 7) and do a clean job of presenting your work. A good part of your grade will be based on how well your executive summary is written. Don’t forget to use units in your table, calculations and plots.